Rock drill bit



FIG. 1 is a front view of a rock drill bit in accordance with my design;

FIG. 2 is a right side view thereof;

FIG. 3 is plan top view thereof;

FIG. 4 is a perspective view thereof;

FIG. 5 is a plan bottom plan view thereof; and,

FIG. 6 is a rear view thereof. 

The ornamental design for a rock drill bit, as shown and described. 